Sinatra before 2.0.2 has XSS via the 400 Bad Request page that occurs upon a params parser exception.
{
"github_reviewed": true,
"cwe_ids": [
"CWE-79"
],
"github_reviewed_at": "2020-06-16T21:46:50Z",
"nvd_published_at": "2018-05-31T19:29:00Z",
"severity": "MODERATE"
}